This invention relates to recessed lighting fixtures. More particularly, the invention relates to recessed lighting fixtures of the type including an incandescent lamp socket enclosure forming a separate portion of the fixture that is substantially displaced from the reflector and other housing portions of the fixture. In still greater particularity, the invention relates to an improvement in these type lighting fixtures providing protection from overheating.
It is becoming increasingly common in the design of recessed lighting fixtures to provide for protection against fire due to fixture overheating. For example, U.S. Pat. Nos. 4,314,223 and 4,450,512 to Paul Kristofek and assigned to the same assignee as the present application disclose a thermal protective device for disconnecting a lamp socket from the power supply when the temperature of the fixture reaches a predetermined level. In U.S. Pat. No. 4,314,223 the thermal protective device is suspended within the interior of the fixture housing between the lamp and the inner surface of the housing wall, and in U.S. Pat. No. 4,450,512, the protective device is mounted on the inner surface of the housing wall to sense the temperature on the outer surface of the housing wall. These structures are effective in protecting recessed fixtures of the type wherein the light source is mounted within the housing or reflector. In such cases the heat generated by both the lamp and the generated within the lamp socket is concentrated and contained within the housing and reflector of the fixture. Therefore, for the most part, substantially all of the sources of heat are monitored. These structures are, however, not able to provide for proper monitoring of heat in those application wherein the sources of heat generated are substantially separated and confined to separate areas such as recessed fixtures incorporating a separate enclosure or neck mounted to and extending from the main housng and reflector and within which the socket for holding the light bulb is mounted. In these type fixtures, heat generated by the bulb is generated within the main housing and reflector and in general is reflected by the reflector out of the housing or at least has greater opportunity to be circulated and safely dissipated. To the contrary, fixtures incorporating a separate socket enclosure isolated from the main housing have less opportunity to dissipate heat generated therein, for example the heat generated by the light socket, because these enclosures are relatively small. The heat generated within these separate enclosures has less opportunity to escape and they can operate at considerably higher temperatures than the main housing. There is, therefore, a need to provide for protection against overheating of those fixtures of the type experiencing two zones of heat concentration.